Load switch integrated circuit and electronic device

ABSTRACT

A load switch integrated circuit and an electronic device are provided. In a case that a surge voltage is applied to an input of the load switch integrated circuit, a surge detection circuit controls a first discharging unit to be switched on to discharge surge energy from an input of the load switch integrated circuit to the ground, and controls a first switch transistor and a second discharging unit to be switched on through a control circuit to discharge surge energy to an output of the load switch integrated circuit to the ground. Compared with a case that surge energy is discharged only by a surge protection circuit in the conventional technology, surge energy is discharged via two paths, and a circuit area is smaller than that in the conventional technology in a case that there is large surge energy to be resisted.

This application claims the priority to Chinese Patent Application No.201711401339.2, titled “LOAD SWITCH INTEGRATED CIRCUIT AND ELECTRONICDEVICE”, filed on Dec. 22, 2017 with the Chinese Patent Office, which isincorporated herein by reference in its entirety.

FIELD

The present disclosure relates to the field of power electronictechnology, and in particular to a load switch integrated circuit and anelectronic device.

BACKGROUND

A surge voltage is a transient over-voltage that is larger than a normaloperation voltage. The surge voltage lasts for an extremely short timeperiod, which is usually in an order of microsecond. When a surge isgenerated, the voltage and the current may be much larger than that in anormal case. When the voltage or the current is larger than an upperlimit of a semiconductor device, the semiconductor device is directlyburnt out. In addition, an accumulation of several slight surges mayalso result in performance degradation of the semiconductor device,thereby shortening the service life of the semiconductor device.

In the conventional technology, a load switch integrated circuit isgenerally arranged preceding a to-be-protected circuit. The load switchintegrated circuit is as shown in FIG. 1. In a case that a surge isgenerated, a main switch transistor M1 is controlled to be switched offby a gate control circuit, thereby protecting a following circuitconnected to an output OUT. However, in a case that the surge isgenerated, a waveform of a voltage at an input IN of the load switchintegrated circuit is represented as a dotted line as shown in FIG. 2.It can be seen that the surge voltage Vsurge is high, which may breakdown and burns out components in the load switch integrated circuit.Therefore, in the conventional technology, a surge protection circuit isadditionally arranged between the input IN and the ground, as shown inFIG. 1. With the surge protection circuit, in a case that the surge isgenerated at the input IN, surge energy is timely discharged to theground and a voltage at the input IN is clamped within an allowed range,which is, for example, a voltage Vclamp shown in FIG. 2, therebyprotecting the components in the load switch integrated circuit, thusprotecting the following circuit from being damaged due to the surgeenergy.

In the conventional technical solution, in order to resist large surgeenergy, it is required that the surge protection circuit has a strongdischarging capacity, which may result in a large circuit area of thesurge protection circuit, and further result in a large area of theentire load switch integrated circuit.

SUMMARY

A load switch integrated circuit and an electronic device are providedaccording to the present disclosure, to solve a problem of a largecircuit area in the conventional technology.

The following technical solutions are provided according to the presentdisclosure.

A load switch integrated circuit is provided, which includes: a firstswitch transistor, a surge detection circuit, a control circuit, a firstdischarging unit and a second discharging unit.

An input of the first switch transistor, an input of the surge detectioncircuit and an input of the first discharging unit are connected to aninput of the load switch integrated circuit.

An output of the first switch transistor and an input of the seconddischarging unit are connected to an output of the load switchintegrated circuit.

An output of the surge detection circuit is connected to a controlterminal of the first discharging unit and an input of the controlcircuit.

An output of the control circuit is connected to a control terminal ofthe first switch transistor and a control terminal of the seconddischarging unit.

An output of the first discharging unit and an output of the seconddischarging unit are grounded.

The surge detection circuit is configured to: detect whether a surgevoltage is applied to the input of the load switch integrated circuit;control, in a case that a surge voltage is applied to the input of theload switch integrated circuit, the first discharging unit to beswitched on to discharge surge energy from the input of the load switchintegrated circuit to the ground; and control, in a case that a surgevoltage is applied to the input of the load switch integrated circuit,the first switch transistor and the second discharging unit to beswitched on through the control circuit to discharge surge energy to theoutput of the load switch integrated circuit to the ground.

In an embodiment, the first discharging unit includes a second switchtransistor, and the second discharging unit includes a third switchtransistor.

In an embodiment, the first switch transistor, the second switchtransistor and the third switch transistor are N-type metal oxidesemiconductor field effect transistors.

In an embodiment, the control circuit includes a fourth switchtransistor. A first output of the surge detection circuit is connectedto a control terminal of the second switch transistor and a controlterminal of the third switch transistor. A second output of the surgedetection circuit is connected to a control terminal of the fourthswitch transistor. An input of the fourth switch transistor is connectedto the control terminal of the first switch transistor. An output of thefourth switch transistor is connected to the control terminal of thethird switch transistor.

In an embodiment, the load switch integrated circuit further includes acharge pump. An output of the charge pump is connected to the controlterminal of the first switch transistor.

In an embodiment, the fourth switch transistor is an N-type metal oxidesemiconductor field effect transistor.

An electronic device is further provided, which includes any one of theload switch integrated circuits described above.

A load switch integrated circuit is provided according to the presentdisclosure. In a case that a surge voltage is applied to an input of theload switch integrated circuit, a surge detection circuit controls afirst discharging unit to be switched on to discharge surge energy froman input of the load switch integrated circuit to the ground, andcontrols a first switch transistor and a second discharging unit to beswitched on through a control circuit to discharge surge energy to anoutput of the load switch integrated circuit to the ground. That is,compared with a case that surge energy is discharged only by a surgeprotection circuit in the conventional technology, in the presentdisclosure, surge energy is discharged via two paths, and a circuit areais smaller than that in the conventional technology in a case that thereis large surge energy to be resisted.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings to be used in the description of the embodiments or theconventional technology are described briefly as follows, so that thetechnical solutions according to the embodiments of the presentdisclosure or according to the conventional technology become clearer.It is apparent that the drawings in the following description onlyillustrate some embodiments of the present disclosure. For those skilledin the art, other drawings may be obtained according to these drawingswithout any creative work.

FIG. 1 is a schematic structural diagram of a load switch integratedcircuit according to the conventional technology;

FIG. 2 is a schematic diagram showing a protection effect of a surgeprotection circuit according to the conventional technology;

FIG. 3 is a schematic structural diagram of a load switch integratedcircuit according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram showing a current discharging path of aload switch integrated circuit according to an embodiment of the presentdisclosure; and

FIG. 5 is a schematic structural diagram of a load switch integratedcircuit according to another embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

The technical solutions according to the embodiments of the presentdisclosure are described clearly and completely in conjunction with thedrawings hereinafter. It is apparent that the described embodiments areonly a few rather than all of the embodiments according to the presentdisclosure. Any other embodiments obtained by those skilled in the artbased on the embodiments of the present disclosure without any creativework should fall within the protection scope of the present disclosure.

A load switch integrated circuit is provided according to the presentdisclosure, to solve a problem of a large circuit area in theconventional technology.

Reference is made to FIG. 3, the load switch integrated circuitincludes: a first switch transistor M1, a surge detection circuit 101, acontrol circuit 102, a first discharging unit 103 and a seconddischarging unit 104.

An input of the first switch transistor M1, an input of the surgedetection circuit 101 and an input of the first discharging unit 103 areconnected to an input IN of the load switch integrated circuit.

An output of the first switch transistor M1 and an input of the seconddischarging unit 104 are connected to an output OUT of the load switchintegrated circuit.

An output of the surge detection circuit 101 is connected to a controlterminal of the first discharging unit 103 and an input of the controlcircuit 102.

An output of the control circuit 102 is connected to a control terminalof the first switch transistor M1 and a control terminal of the seconddischarging unit 104.

An output of the first discharging unit 103 and an output of the seconddischarging unit 104 are grounded.

The surge detection circuit 101 is configured to detect whether a surgevoltage is applied to the input IN of the load switch integratedcircuit. In a case that a surge voltage is applied to the input IN ofthe load switch integrated circuit, the surge detection circuit 101outputs two signals. The first discharging unit 103 is controlled to beswitched on in response to one signal outputted by the surge detectioncircuit 101, to discharge surge energy from the input IN of the loadswitch integrated circuit to the ground, and the first switch transistorM1 and the second discharging unit 104 are controlled to be switched onby the control circuit 102 in response to the other signal outputted bythe surge detection circuit 101, to discharge surge energy to the outputOUT of the load switch integrated circuit to the ground, therebyachieving two-path surge energy discharging.

In an embodiment, as shown in FIG. 3, the first discharging unit 103includes a second switch transistor M2, and the second discharging unit104 includes a third switch transistor M3.

In an embodiment, the first switch transistor M1, the second switchtransistor M2 and the third switch transistor M3 are N-type metal oxidesemiconductor field effect transistors, which may operate under a highpower.

The first switch transistor M1 is a main switch transistor of the loadswitch integrated circuit. In a case that it is required to switch onthe load switch integrated circuit, the first switch transistor M1 isswitched on to connect the input IN of the load switch integratedcircuit with the output OUT of the load switch integrated circuit, andVOUT=VIN. In a case that it is required to switch off the load switchintegrated circuit, the first switch transistor M1 is switched off.

In a case that the surge detection circuit 101 detects that a surgevoltage is applied to the input IN of the load switch integratedcircuit, the second switch transistor M2 is switched on by increasing avoltage at a gate Gate 2 of the second switch transistor M2 to a voltagecapable of switching on the second switch transistor M2, to dischargethe surge energy from the input IN of the load switch integrated circuitto the ground via a path thus formed. In a case that the surge voltagedisappears, the second switch transistor M2 is switched off by shortingthe gate Gate 2 of the second switch transistor M2 to the ground. Sincethe second switch transistor M2 is always in a switched-off state in acase that no surge voltage is applied, the operation of other circuitsis not affected.

In a structure shown in FIG. 3, in addition to the second switchtransistor M2, the surge protection function may also be achieved bycooperation of the first switch transistor M1 and the third switchtransistor M3. Specifically, in a case that a surge is generated, thesecond switch transistor M2 is switched on to form a first path (a pathI1 shown in FIG. 4) for discharging the surge energy. In addition, thefirst switch transistor M1 is switched on by clamping a voltage at agate Gate 1 of the first switch transistor M1 to a voltage capable ofswitching on the first switch transistor M1, and the third switchtransistor M3 is switched on by increasing a voltage at a gate Gate 3 ofthe third switch transistor M3 to a voltage capable of switching on thethird switch transistor M3. The first switch transistor M1 and the thirdswitch transistor M3 are connected with each other in series to form asecond path (a path 12 shown in FIG. 4) for discharging the surgeenergy. Since the second switch transistor M2 and the third switchtransistor M3 are always in a switched-off state in a case that no surgevoltage is applied, the operation of other circuits is not affected.

Compared with a case that the surge energy is discharged only by a surgeprotection circuit in the conventional technology, with the load switchintegrated circuit according to the present disclosure, the surge energyis discharged via two paths. A second path is additionally arranged fordischarging the surge energy, such that the surge protection capabilityof a chip is improved, and the circuit area is smaller than that in theconventional technology in a case that there is large surge energy to beresisted.

It is to be noted that the discharging unit may also be implemented byanother controllable device, as long as the controllable device has acertain discharging capability and a small circuit area, which shouldfall within the protection scope of the present disclosure.

A load switch integrated circuit is further provided according toanother embodiment of the present disclosure. Based on the aboveembodiment and FIGS. 3 and 4, in an embodiment, as shown in FIG. 5, thecontrol circuit 102 includes a fourth switch transistor M4.

A first output of the surge detection circuit 101 is connected to acontrol terminal of the second switch transistor M2 and a controlterminal of the third switch transistor M3.

A second output of the surge detection circuit 101 is connected to acontrol terminal of the fourth switch transistor M4.

An input of the fourth switch transistor M4 is connected to the controlterminal of the first switch transistor M1.

An output of the fourth switch transistor M4 is connected to the controlterminal of the third switch transistor M3.

In an embodiment, as shown in FIG. 5, the load switch integrated circuitfurther includes a charge pump 105. An output of the charge pump 105 isconnected to the control terminal of the first switch transistor M1.

In an embodiment, the fourth switch transistor M4 is an N-type metaloxide semiconductor field effect transistor.

As shown in FIG. 5, in a case that it is required to switch on the firstswitch transistor M1, a voltage at the gate Gate 1 of the first switchtransistor M1 is increased to be higher than a voltage at the output OUTby the charge bump 105, to switch on the first switch transistor M1. Inaddition, the first switch transistor M1 may be switched off also bymeans of the charge pump 105. A gate of the second switch transistor M2and a gate of the third switch transistor M3 are shorted together, whichare controlled by the surge detection circuit 101. In a case that nosurge is generated, the gate Gate 3 of the third switch transistor M3 isgrounded. In a case that a surge is generated, the fourth switchtransistor M4 is switched on, and the gate Gate 1 of the first switchtransistor M1 is shorted to the gate Gate 3 of the third switchtransistor M3, to increase a voltage at the gate Gate 3 of the thirdswitch transistor M3 to a certain voltage (for example, 5V) under thecontrol of the surge detection circuit 101. In this case, the firstswitch transistor M1, the second switch transistor M2 and the thirdswitch transistor M3 are all switched on, to discharge the surge energytogether. Since the voltage at the gate Gate 1 of the first switchtransistor M1 is clamped to be a low voltage, the voltage at the outputOUT may not be increased excessively in a case that a surge isgenerated, thereby protecting a device connected to the output OUT frombeing damaged due to the surge.

Other structures and principles are the same as that described in theabove embodiments, which is not repeated herein.

An electronic device is further provided according to another embodimentof the present disclosure, which includes a load switch integratedcircuit described in any one of the above embodiments.

Specifically, the electronic device may be a mobile terminal such as acell phone and a tablet computer, or another universal serial bus (USB)interface device, which is not specifically limited herein. Anyelectronic device including the load switch integrated circuit describedin the above embodiment should fall within the protection scope of thepresent disclosure.

The embodiments of the present disclosure are described in a progressivemanner, and each embodiment places emphasis on the difference from otherembodiments. Therefore, for the same or similar parts between theembodiments, one may refer to the description of other embodiments. Forthe device according to the embodiments, the device corresponds to themethod according to the embodiments. Therefore, the description thereofis simple, and for the related parts, one may refer to the descriptionof the method embodiments.

What is described above is only preferred embodiments of the presentdisclosure and is not intended to limit the present disclosure in anyway. The preferred embodiments of the present disclosure are disclosedabove, which should not be interpreted as limiting the presentdisclosure. Numerous alternations, modifications, and equivalents can bemade to the technical solutions of the present disclosure by thoseskilled in the art in light of the methods and technical contentdisclosed herein without deviation from the scope of the presentdisclosure. Therefore, any alternations, modifications, and equivalentsmade to the embodiments above according to the technical essential ofthe present disclosure without deviation from the scope of the presentdisclosure should fall within the scope of protection of the presentdisclosure.

The invention claimed is:
 1. A load switch integrated circuit,comprising: a first switch transistor; a surge detection circuit; acontrol circuit; a first discharging unit; and a second dischargingunit, wherein an input of the first switch transistor, an input of thesurge detection circuit and an input of the first discharging unit areconnected to an input of the load switch integrated circuit, an outputof the first switch transistor and an input of the second dischargingunit are connected to an output of the load switch integrated circuit,an output of the surge detection circuit is connected to a controlterminal of the first discharging unit and an input of the controlcircuit, an output of the control circuit is connected to a controlterminal of the first switch transistor and a control terminal of thesecond discharging unit, an output of the first discharging unit and anoutput of the second discharging unit are grounded, and the surgedetection circuit is configured to: detect whether a surge voltage isapplied to the input of the load switch integrated circuit; control, ina case that a surge voltage is applied to the input of the load switchintegrated circuit, the first discharging unit to be switched on todischarge surge energy from the input of the load switch integratedcircuit to the ground; and control, in a case that a surge voltage isapplied to the input of the load switch integrated circuit, the firstswitch transistor and the second discharging unit to be switched onthrough the control circuit to discharge surge energy to the output ofthe load switch integrated circuit to the ground.
 2. The load switchintegrated circuit according to claim 1, wherein the first dischargingunit comprises a second switch transistor, and the second dischargingunit comprises a third switch transistor.
 3. The load switch integratedcircuit according to claim 2, wherein the first switch transistor, thesecond switch transistor and the third switch transistor are N-typemetal oxide semiconductor field effect transistors.
 4. The load switchintegrated circuit according to claim 2, wherein the control circuitcomprises a fourth switch transistor, and wherein a first output of thesurge detection circuit is connected to a control terminal of the secondswitch transistor and a control terminal of the third switch transistor,a second output of the surge detection circuit is connected to a controlterminal of the fourth switch transistor, an input of the fourth switchtransistor is connected to the control terminal of the first switchtransistor, and an output of the fourth switch transistor is connectedto the control terminal of the third switch transistor.
 5. The loadswitch integrated circuit according to claim 4, further comprising acharge pump, wherein an output of the charge pump is connected to thecontrol terminal of the first switch transistor.
 6. The load switchintegrated circuit according to claim 4, wherein the fourth switchtransistor is an N-type metal oxide semiconductor field effecttransistor.
 7. An electronic device, comprising a load switch integratedcircuit, wherein the load switch integrated circuit comprises: a firstswitch transistor, a surge detection circuit, a control circuit, a firstdischarging unit and a second discharging unit, and wherein an input ofthe first switch transistor, an input of the surge detection circuit andan input of the first discharging unit are connected to an input of theload switch integrated circuit, an output of the first switch transistorand an input of the second discharging unit are connected to an outputof the load switch integrated circuit, an output of the surge detectioncircuit is connected to a control terminal of the first discharging unitand an input of the control circuit, an output of the control circuit isconnected to a control terminal of the first switch transistor and acontrol terminal of the second discharging unit, an output of the firstdischarging unit and an output of the second discharging unit aregrounded, and the surge detection circuit is configured to: detectwhether a surge voltage is applied to the input of the load switchintegrated circuit; control, in a case that a surge voltage is appliedto the input of the load switch integrated circuit, the firstdischarging unit to be switched on to discharge surge energy from theinput of the load switch integrated circuit to the ground; and control,in a case that a surge voltage is applied to the input of the loadswitch integrated circuit, the first switch transistor and the seconddischarging unit to be switched on through the control circuit todischarge surge energy to the output of the load switch integratedcircuit to the ground.
 8. The electronic device according to claim 7,wherein the first discharging unit comprises a second switch transistor,and the second discharging unit comprises a third switch transistor. 9.The electronic device according to claim 8, wherein the first switchtransistor, the second switch transistor and the third switch transistorare N-type metal oxide semiconductor field effect transistors.
 10. Theelectronic device according to claim 8, wherein the control circuitcomprises a fourth switch transistor, and wherein a first output of thesurge detection circuit is connected to a control terminal of the secondswitch transistor and a control terminal of the third switch transistor,a second output of the surge detection circuit is connected to a controlterminal of the fourth switch transistor, an input of the fourth switchtransistor is connected to the control terminal of the first switchtransistor, and an output of the fourth switch transistor is connectedto the control terminal of the third switch transistor.
 11. Theelectronic device according to claim 10, the load switch integratedcircuit further comprises a charge pump, wherein an output of the chargepump is connected to the control terminal of the first switchtransistor.
 12. The electronic device according to claim 10, wherein thefourth switch transistor is an N-type metal oxide semiconductor fieldeffect transistor.